In response to a question I asked earlier today,
cianoz provided a very helpful answer
straight from the end of the perlvar man page.

However, I do make it a point to RTFM before I ask.
I had already looked over perlman:perlvar on-line here
and hadn't seen the section cianoz quoted.
It turns out that it's one of two sections
at the end of the perlvar man page
("Technical Note on the Syntax of Variable Names" and "BUGS"),
that simply aren't there in the on-line document.
(And they're not just missing from here, either; the
perlvar
doc over at
http://www.perl.com
is the same as the one here at perlmonks.)

My man pages are from 5.6.0,
and I don't find an identifying version number
in the on-lines copies,
so is this just a version difference?

you are correct that the problem is version skew. if i
recall, the suggestion has come up before of labelling the
perlman:* pages with a version number. i thought it was a
good idea then, and continue to believe so now.

update: just for the record, i agree
with merlyn (infra) that it is not time to update the Perl
Monks perlman pages from 5.005x yet. i was suggesting only
a label.